Statistical Significance

Topic 8

what is a significant difference?

difference between variables that is influenced systematically and not by chance

what is a significance level?

level of risk taken that says statistical occurrence is by chance

what is statistical difference?

it indicates that a difference between two groups is unlikely due to random chance

what is a p value?

the value that determines if a test is statistically significant

Tyle 1 error?

rejecting the null when it is true

Type II error?

the alternative hypothesis is correct

how is type I error in your control?

related to your risk in statistical significance

what factors influence type II error?

sample size and sample characteristics

what is a critical value?

used to decide if a statistic ic extreme enough to reject the null hypothesis

how does a critical value relate to the chosen significance level?

it corresponds to the chosen significance level, which is usually 0.05

In terms of critical values, when do we reject the null hypothesis?

if the test statistic exceeds the critical value

when is a one-tailed test used?

used to determine a direction for a research question

when is a two-tailed test used?

to determine if there is a relationship at all

what is the common critical value for a two-tailed test?

±1.96

what is the common critical value for a one-tailed test?

±1.645

what does crossing the critical value indicate?

the result is statistically significant and not due to chance

what is a confidence interval?

contains a range of values that likely contains the true value of a population parameter within a certain confidence interval

how do you calculate the confidence interval?

calculate sample mean, determine standard error, find the critical value-large samples use 1.96, calculate the margin of error, construct the interval (lower=Mean-ME, higher=Mean+Me)

what is the margin of error calculation?

Critical Value x SE(standard error)